Selection of ferrite powder for thermal coagulation therapy with alternating magnetic field

Selection of ferrite powder was carried out to realize a thermal coagulation technique in which tumors are locally heated by an application of alternating magnetic field from external coils. Magnesium ferrite (MgFe2O4) showed the largest increase in temperature ( T ) under an alternating magnetic field in all the ferrites examined. For all the samples, T value under alternating magnetic field was increased with an increase in frequency (200–500 kHz). The heating ability for the Mg-ferrite was ca. 1.4 W/g under alternating magnetic field of 4.0 kA/m (200 W, 370 kHz). The heating ability in alternating magnetic field was clearly depended on the magnitude of the hysteresis loss for the ferrite powder. C 2005 Springer Science + Business Media, Inc.